i see it as a slap in the face of the original z28. a 427 wasn't an option for a z28. what option code got that engine . . . . oh yeah that pesky zL1. i think the zL1 should've gotten the LS7 seeing as how the ZL1 was the only car that came with a 427 and kept everything else how it is and the z28 should've gotten the LSA engine since a 302 is out of the question for the modern day enthusiasts mentality of no replacement for discplacement.
Also showing these numbers from factory the z28 was not the fastest car in the lineup, pretty much only faster than the ss350 in 67 and most likely faster than the 69 ss350 but i couldn't find a factory time slip for it :(
1967
(Z-28) 302/290bhp: 0-60 in 6.9 sec, 1/4 mile in 14.85 sec @ 101mph
(SS350) 350/295: 1/4 mile in 15.4 seconds @ 90 mph
(SS396) 396/325bhp: 0-60 in 6.0 sec, 1/4 mile in 14.5 sec @ 99mph
1969(Z-28) 302/290bhp: 0-60 in 7.4 sec, 1/4 mile in 15.12 sec @ 94.8mph
(SS396) 396/375bhp: 0-60 in 6.8 sec, 1/4 mile in 14.7 sec @ 98.7mph
(COPO 9561) 427/425bhp: 0-60 in 5.4 sec, 1/4 mile in 13.5 sec @ 102mph
(COPO 9560) 427/430bhp: 0-60 in 5.3 sec, 1/4 mile in 13.16 sec @ 110 mph

The Z/28 was not about straight line speed, it was about cornering. The 302 engine was not a choice by GM, it was required by the Trans Am racing series. The LS7 in the Z/28 is acceptable because the LS7 is built for racing and there is no displacement cap so why not go big?